The present invention relates to bulk material conveyors in general and, in particular, to a new and useful method of analyzing the solid matter content of a hydraulic conveying stream to be monitored and controlled, which contains a carrier liquid and solid particles, and to a device for carrying out the method.
In the hydraulic transportation of mineral material, such as coal, ore, etc., it is well known that the proportion of solid matter to carrier liquid is of fundamental importance for maintaining a continuous conveying stream. German Auslegungschrift No. 2,557, 872, which is here incorporated by reference for background information, for example, discloses a method according to which the solid matter to be conveyed, after being broken up into fragments of a suitable size is combined with a stream of carrier liquid to obtain a two-phase pumpable slurry. That is, a slurry with a liquid part and a particle part is obtained. The objective of this prior art method is to obtain a substantially constant weight rate of flow of the slurry through the pipeline and to automatically control the solid matter concentration in the slurry to keep it at a substantially constant value.
Experience has shown that the prior art methods and arrangements are not satisfactory for maintaining an undisturbed continuous material flow in the pipeline. The present invention is based on the observation and experience that, despite careful monitoring and control of the proportions of solid matter and carrier liquid, a trouble-free hydraulic transportation of minerals in pipelines cannot be insured because, along extended conveying sections, the flow conditions continue to vary even if the solid matter-to-carrier liquid proportion remains constant.
This condition is apparently caused by a continual frictional contact of the solid particles with each other and with the pipe walls, resulting in a varying particle size distribution within the entire solid matter proportion. This variation of the particle size distribution necessarily changes the consistency and, thus, the flow conditions of the slurry to be conveyed so that, for example, due to an increase in the critical speed of conveyance and to deposits in the line, a continuous flow is no longer insured.